Lab 5 - Electron Charge-to-Mass Ratio

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "Lab 5 - Electron Charge-to-Mass Ratio"

Transcription

1 Lab 5 Electron Charge-to-Mass Ratio L5-1 Name Date Partners Lab 5 - Electron Charge-to-Mass Ratio OBJECTIVES To understand how electric and magnetic fields impact an electron beam To experimentally determine the electron charge-to-mass ratio OVERVIEW In this experiment, you will measure e/m, the ratio of the electron s charge e to its mass m. Given that it is also possible to perform a measurement of e alone (the Millikan Oil Drop Experiment), it is possible to obtain the value of the mass of the electron, a very small quantity. If a particle carrying an electric charge q moves with a velocity v in a magnetic field B that is at a right angle to the direction of motion, it will experience the Lorentz force: F = qv B (5.1) Which, because of the vector product, is always perpendicular to both the magnetic field and the direction of motion. A constant force that is always perpendicular to the direction of motion will cause a particle to move in a circle. We will use this fact to determine e/m of the electron by measuring the radius of that circle. To this end we must: produce a narrow beam of electrons of known energy, produce a uniform magnetic field, find a way to measure the radius R of the circular orbit of the electrons in that magnetic field, and find the relation between that radius and the ratio e/m. We will discuss these tasks in order. The Electron Beam When one heats a piece of metal, say a wire, to 1,000 K or beyond, electrons will boil off from its surface. If one surrounds the wire with a positively charged electrode, an anode, the

2 L5-2 Lab 5 Electron Charge-to-Mass Ratio electrons will be attracted to it and move radially outward as indicated in Figure 5.1. On their way to the anode they will acquire a kinetic energy E k = 1 2 mv2 = ev, (5.2) where V is the potential difference, or voltage, between the heated filament, called the cathode, and the anode. Figure 5.1: Most of the electrons will strike the anode. However, if one cuts a narrow slit into the anode, those electrons that started out toward the slit will exit through it as a narrow beam with a kinetic energy E k. The Magnetic Field According to Ampere s law a wire carrying a current I is surrounded by a magnetic field B, as shown in Figure 5.2. If the wire is bent into a circle the field lines from all sides reinforce each other at the center, creating an axial field (see Figure 5.3). Usually one will not use a single loop of wire to create a field but a coil with many turns. ). Figure 5.2: Magnetic field of a straight wire Figure 5.3: Magnetic field of a wire loop

3 Lab 5 Electron Charge-to-Mass Ratio L5-3 If one uses two coaxial coils of radius R that are a distance d apart, as shown in Figure 5.4, the field at the center point between the coils will be nearly homogeneous 1. H. von Helmholtz ( ) realized that there remains a free parameter, namely the coil separation d, that can still be adjusted. He showed that when d = R, the result is a particularly homogeneous field in the central region between the coils. 2 Since that time Helmholtz coils have been used when there is a need for homogeneous magnetic fields. Figure 5.4: Magnetic field B of a pair of Helmholtz coils One can show that the field in the center of a Helmholtz coil is given by ( ) 8Nµ0 B = 5R I, (5.3) 5 where I is the current flowing through both coils, R is their mean radius, N is the number of turns of wire in each coil, and µ 0 = 4π 10 7 T m/a is the permeability constant. The Electron Orbit Experiments like the one that you will perform have been used to measure the mass of charged particles with great precision. In these experiments the particles move in a circular arc whose beginning and end are measured very accurately in a near perfect vacuum. For our simple experiment we cannot go to such lengths and a simple expedient has been used to make the electron orbit visible. The bulb surrounding the electron source is filled with helium vapor. When the electrons collide with the atoms, the atoms emit light so that one can follow the path of the electron beam. These collisions will diminish the accuracy of the experiment but it remains adequate for our purposes. A particle moving in a circle of radius R must be held there by a centripetal force F c = mv2 r. (5.4) In our case, that centripetal force is the Lorentz force, Equation (5.1), hence evb = mv2 (5.5) r This equation contains the velocity V, which we can eliminate by using Equation (5.2). Rewriting Equation (5.2), we find 1 The symmetry of the arrangement makes the first derivative of the field with respect to the axial direction vanish. 2 The second derivative vanishes as well.

4 L5-4 Lab 5 Electron Charge-to-Mass Ratio v = 2eV m (5.6) and hence e m = 2V B 2 r 2 = R 2 V (NIµ 0 r) 2 (5.7) In this equation, V is the voltage between cathode and anode and r is the mean radius of the circular electron orbit, both of which can be measured, and B is the magnetic field through which the electrons pass. We know the magnetic field at the center of the Helmholtz coil, which can be obtained, using Equation (5.3), from a measurement of the current through the coils, the dimension of the coils and the number of turns. The magnetic field does not change very much away from the center of the coils. INVESTIGATION 1: Finding e/m For this investigation, you will need the following: Helmholtz coil with e/m glass tube Bar magnet 3-m measuring tape Flashlight Incandescent light for reading manual Activity 1-1: The e/m Apparatus In this activity, you will familiarize yourself with the setup you will be using.

5 Lab 5 Electron Charge-to-Mass Ratio L5-5 Figure 5.5: e/m Apparatus Question 1-1: When you first observe the electron beam in this lab, the electrons will proceed straight down. As you turn up the current in the Helmholtz coils, the electrons will curve to the left. As you look at the apparatus shown in Figure 5, in what direction is the magnetic field, and in what describe the flow of current (positive) in the coils. 1. Turn the main power on. The unit will perform a self test lasting no more than 30 s. Do not do anything with the unit during the self test. When it is finished, the coil current display will be stabilized and indicate 000. The unit is now ready to use, but note that there is a ten minute warm-up time before you should take final measurements. You can go ahead and proceed with the remainder of this procedure. 2. Look in the center of the Helmholtz coils for the glass tube. The tube is extremely fragile, and the wires sticking out from the tube have current and voltage, so be very careful. This evacuated glass tube has a tiny bit of helium vapor inside. The electrons will follow circular orbits inside this tube and collide with and ionize the helium atoms, causing the gas to glow and making the beam visible. 3. Locate the grid and anode inside the glass tube. It is the pair of vertically oriented metal cylinders with a gap between them. At its top and center is the filament or cathode that will be heated by a current to emit the electrons. You should be able to easily see the filament, because it will be brightly lit. 4. There are three separate electrical circuits: (a) Filament/cathode heater (over which you have no control); (b) Accelerating Voltage between cathode and anode;

6 L5-6 Lab 5 Electron Charge-to-Mass Ratio (c) Coil Current for the Helmholtz coils. Figure 5.6: Cathode, Grid and Anode. The electrons are accelerated down from the cathode to the anode. Their initial direction is down and their path of motion will be bent to the left in the above diagram by the magnetic field 5. Measure the diameter of the Helmholtz coils in several places and take the average. Record the mean radius R and the standard error below. Radius R : ± cm 6. Measure the mean separation d between the coils. You may want to average several measurements here also. Coil separation d: cm Verify that d R. (Note: We have found they may not quite agree.) 7. The manufacturer states that there are 130 turns in each coil. 8. Calculate the constant of proportionality between the current passing through the Helmholtz coils and the magnetic field produced. You will need the above parameters to do this. Look at Equation (5.3). Show your work. B Helmholtz (Tesla) = I (amps)

7 Lab 5 Electron Charge-to-Mass Ratio L5-7 Prediction 1-1: The nominal magnetic field value for the apparatus you will be using is 1.3 mt (millitesla). The Earth s magnetic field is approximately 0.1 mt and is pointing into the ground at an angle of about 66 with respect to the horizontal. Discuss how much difficulty the Earth s magnetic field will cause in your experiment. Do this before coming to lab. Your TA will check. Prediction 1-2: If it were possible to arbitrarily orient the apparatus, in what direction (parallel, anti-parallel, perpendicular, other) should it be aligned in order to minimize the effects of the Earth s magnetic field? Explain your reasoning. Use Figure 5.6. Do this before coming to lab. NOTE: We can not compensate for the Earth s magnetic field with this apparatus. 9. Turn up the voltage adjust knob to a voltage of 300 V. Look for the electron beam, which should be pointing down. Turn up the current adjust knob and look at the path of the electron beam. 10. You should also be able to see the filament (wires that are glowing orange due to being heated). NOTE: Both the voltage and current outputs are controlled by a microprocessor, which locks out the controls at both the minimum and maximum settings. There is not a manual stop on the knobs. When the knob reaches the maximum setting, it will still turn, but the appropriate value will not change. This feature prevents excessive voltage being applied to the tube or excessive current through the coils. 11. Turn the Current Adjust control up and observe the circular deflection of the beam. When the current is high enough, the beam will form a circle. The diameter of the electron path in the magnetic field can be measured using the etched glass internal scale in the tube. The graduations and numerals of the scale are illuminated by the collision of the electrons, making observation reading fairly easy. Vary the Current Adjust and note the electron beam striking several of the centimeter scale markings. You should also be able to see a vertical line indicating the half-centimeter mark. The scale numbers fluoresce when the beam hits them. NOTE: Sometimes the electron beam slightly misses the internal glass scale tube. DO NOT TRY TO MAKE ANY ADJUSTMENTS! Sometimes it helps to put a dim backlight behind the scale to help see the numbers and half-centimeter marks. [If it is really bad, ask your TA to look at it.]

8 L5-8 Lab 5 Electron Charge-to-Mass Ratio 12. Describe what happens to the beam of electrons as the coil current is increased: Question 1-2: What causes this behavior in step 12? 13. Set the coil current to 1.7 A. Adjust the accelerating voltage while looking at the electron beam path. Question 1-3: What do you observe as the accelerating voltage is changed while keeping the coil current constant? Explain why this occurs. 14. While the electron beam is somewhere near the middle of the glass rod, use the bar magnet to see how it affects the electron beam. Question 1-4: Describe what you observe as you move the bar magnet around. Can you produce a helical path for the electron? Can you see why you want to keep spurious magnetic fields away from the electron beam? 15. Make sure you place the bar magnet at the other end of the table from your apparatus to minimize any possible effects.

9 Lab 5 Electron Charge-to-Mass Ratio L5-9 Activity 1-2: Measurement Of Charge-To-Mass Ratio NOTE: The electrons collide with the helium gas atoms that were introduced to make the beam visible. Unavoidably, the electrons lose some energy in the collisions (that make the beam visible). In order to minimize this effect, you should concentrate on those electrons that have the highest energy: those at the outer edge of the beam (largest radius). Ask your TA if you are uncertain about this. 1. We will make measurements for the electrons moving in various circular orbits. You will write down the diameter of the path by reading the illuminated tube. You will need these in order to determine e/m from Equation (5.7). 2. Set the anode voltage to 300 V. Change the coil current until the beam hits the 5 cm mark. This will be the diameter, not the radius. Record the coil current and diameter in Table 5.1. Decrease the coil current in turn to go through each 0.5 cm of the diameter. The 0.5 cm marks are a vertical line between the numbered cm marks. This can proceed quite rapidly by one person observing the beam while changing the coil current and another person filling in Table Proceed in turn to observe and record data for the other accelerating voltages in Table 5.1. Sometimes the beam will physically not be present for every position listed in Table 5.1. Leave the table blank when this occurs. 4. Turn the main power off. Diameter (cm) Accelerating (anode) Voltage 250 V 300 V 350 V 400 V 450 V 500 V Coil Coil Coil Coil Coil Coil Current Current Current Current Current Current (A) (A) (A) (A) (A) (A) Table 5.1: 5. Open up Excel file L05.Table1-1.xls to calculate the values for e/m for each of your data points. Notice that there are two sheets (tabs) for this file (at bottom). You put your Coil

10 L5-10 Lab 5 Electron Charge-to-Mass Ratio Current data into the sheet labeled Data. The sheet labeled e/m uses that data to determine e/m. If you change the format of the data sheet, the e/m calculation will not work properly. Don t forget to insert the constants R and number of turns N. 6. Click on the tab sheet for e m and make sure that the e/m values have been calculated for all the cells with data. Delete the results for those calculations without data. In this case, you will probably see an error message. Average all your experimental results in Excel to obtain a mean value for e/m. Show this result and all subsequent calculations on your Excel file. e/m: x C/kg 7. Find the statistical error of your average value. [Hint: Think standard error of the mean ] Standard error of mean: x C/kg 8. What number is your apparatus? Question 1-5: Discuss how well your result compares with the accepted value of e/m = 1.759x10 11 C/kg within the statistical error. 9. Print out one Excel data table for your group. Do not delete your Excel file. You will need it later. Activity 1-3: Investigation of Systematic Error It is useful in an experiment like this to see if there are systematic errors that might affect your final results. From Equations (5.7) and (5.3) [and a review of Appendix C, of course!] we can see that the relative error in our experimental determination of e/m due to errors in our measured quantities (V, I, R, and r) is given by: ( σe/m e/m ) 2 = ( σv ) 2 ( + 2 σ I V I ) 2 + ( 2 σ R R ) 2 + ( 2 σ r r ) 2 (5.8)

11 Lab 5 Electron Charge-to-Mass Ratio L5-11 Question 1-6: With Equation (5.7) in mind, discuss possible sources of error in your experiment. 1. It is possible that we may learn something about our errors if we compare the values of e/m versus our parameters. Because we have our data in Excel, it is quite easy to do that. 2. Make three plots. Plot all your values of e/m versus each of the following. (a) accelerating voltage, (b) coil current, and (c) orbit radius. Excel Plots: (a) Highlight column of data you want in x-axis (b) Press and hold down Control button while highlighting data you want on the y-axis. (c) Go to Chart Wizzard icon and choose scatter plot (d) Put on labels, etc Place labels and units on the two axes and label the groupings of values on the plot. 3. Print out one copy each of these three graphs and include them in your report. Question 1-7: Look carefully at the plot versus accelerating voltage. Do you see any patterns? Could these possibly indicate any systematic problems? Discuss these possible errors and how you might be able to correct for them or improve the experiment. Question 1-8: Look carefully at the plot versus coil current. Do you see any patterns? Could these possibly indicate any systematic problems? Discuss these possible errors and how you might be able to correct for them or improve the experiment.

12 L5-12 Lab 5 Electron Charge-to-Mass Ratio Question 1-9: Look carefully at the plot versus orbit radius. Do you see any patterns? Could these possibly indicate any systematic problems? Discuss these possible errors and how you might be able to correct for them or improve the experiment. Question 1-10: List any other systematic errors you can think of and discuss. Please clean up your lab area and make sure that the power on the apparatus is off

LAB 8: Electron Charge-to-Mass Ratio

LAB 8: Electron Charge-to-Mass Ratio Name Date Partner(s) OBJECTIVES LAB 8: Electron Charge-to-Mass Ratio To understand how electric and magnetic fields impact an electron beam To experimentally determine the electron charge-to-mass ratio.

More information

E/M Experiment: Electrons in a Magnetic Field.

E/M Experiment: Electrons in a Magnetic Field. E/M Experiment: Electrons in a Magnetic Field. PRE-LAB You will be doing this experiment before we cover the relevant material in class. But there are only two fundamental concepts that you need to understand.

More information

Measurement of Charge-to-Mass (e/m) Ratio for the Electron

Measurement of Charge-to-Mass (e/m) Ratio for the Electron Measurement of Charge-to-Mass (e/m) Ratio for the Electron Experiment objectives: measure the ratio of the electron charge-to-mass ratio e/m by studying the electron trajectories in a uniform magnetic

More information

CHARGE TO MASS RATIO OF THE ELECTRON

CHARGE TO MASS RATIO OF THE ELECTRON CHARGE TO MASS RATIO OF THE ELECTRON In solving many physics problems, it is necessary to use the value of one or more physical constants. Examples are the velocity of light, c, and mass of the electron,

More information

Date: Deflection of an Electron in a Magnetic Field

Date: Deflection of an Electron in a Magnetic Field Name: Partners: Date: Deflection of an Electron in a Magnetic Field Purpose In this lab, we use a Cathode Ray Tube (CRT) to measure the effects of an electric and magnetic field on the motion of a charged

More information

Motion of Charges in Combined Electric and Magnetic Fields; Measurement of the Ratio of the Electron Charge to the Electron Mass

Motion of Charges in Combined Electric and Magnetic Fields; Measurement of the Ratio of the Electron Charge to the Electron Mass Motion of Charges in Combined Electric and Magnetic Fields; Measurement of the Ratio of the Electron Charge to the Electron Mass Object: Understand the laws of force from electric and magnetic fields.

More information

Modern Physics Laboratory e/m with Teltron Deflection Tube

Modern Physics Laboratory e/m with Teltron Deflection Tube Modern Physics Laboratory e/m with Teltron Deflection Tube Josh Diamond & John Cummings Fall 2010 Abstract The deflection of an electron beam by electric and magnetic fields is observed, and the charge

More information

Electron Charge to Mass Ratio Matthew Norton, Chris Bush, Brian Atinaja, Becker Steven. Norton 0

Electron Charge to Mass Ratio Matthew Norton, Chris Bush, Brian Atinaja, Becker Steven. Norton 0 Electron Charge to Mass Ratio Matthew Norton, Chris Bush, Brian Atinaja, Becker Steven Norton 0 Norton 1 Abstract The electron charge to mass ratio was an experiment that was used to calculate the ratio

More information

Lab 4: Magnetic Force on Electrons

Lab 4: Magnetic Force on Electrons Lab 4: Magnetic Force on Electrons Introduction: Forces on particles are not limited to gravity and electricity. Magnetic forces also exist. This magnetic force is known as the Lorentz force and it is

More information

6/2016 E&M forces-1/8 ELECTRIC AND MAGNETIC FORCES. PURPOSE: To study the deflection of a beam of electrons by electric and magnetic fields.

6/2016 E&M forces-1/8 ELECTRIC AND MAGNETIC FORCES. PURPOSE: To study the deflection of a beam of electrons by electric and magnetic fields. 6/016 E&M forces-1/8 ELECTRIC AND MAGNETIC FORCES PURPOSE: To study the deflection of a beam of electrons by electric and magnetic fields. APPARATUS: Electron beam tube, stand with coils, power supply,

More information

J. J. Thomson's Measurement of e/m for the electron

J. J. Thomson's Measurement of e/m for the electron Physics 165 Laboratory J. J. Thomson's Measurement of e/m for the electron In 1897, the cathode ray tube or CRT, which is now a part of most TV sets, was the last word in advanced laboratory instrumentation

More information

Deflection of Electrons in an Electric Field

Deflection of Electrons in an Electric Field Name: Partners: Date: Deflection of Electrons in an Electric Field Purpose In this lab, we use a Cathode Ray Tube (CRT) to measure the effects of an electric field on the motion of a charged particle,

More information

Charge and Mass of the Electron

Charge and Mass of the Electron PHY 19 Charge and Mass of the Electron 1 Charge and Mass of the Electron Motivation for the Experiment The aim of this experiment is to measure the charge and mass of the electron. The charge will be measured

More information

Homework #8 203-1-1721 Physics 2 for Students of Mechanical Engineering. Part A

Homework #8 203-1-1721 Physics 2 for Students of Mechanical Engineering. Part A Homework #8 203-1-1721 Physics 2 for Students of Mechanical Engineering Part A 1. Four particles follow the paths shown in Fig. 32-33 below as they pass through the magnetic field there. What can one conclude

More information

Force on Moving Charges in a Magnetic Field

Force on Moving Charges in a Magnetic Field [ Assignment View ] [ Eðlisfræði 2, vor 2007 27. Magnetic Field and Magnetic Forces Assignment is due at 2:00am on Wednesday, February 28, 2007 Credit for problems submitted late will decrease to 0% after

More information

Physics 41, Winter 1998 Lab 1 - The Current Balance. Theory

Physics 41, Winter 1998 Lab 1 - The Current Balance. Theory Physics 41, Winter 1998 Lab 1 - The Current Balance Theory Consider a point at a perpendicular distance d from a long straight wire carrying a current I as shown in figure 1. If the wire is very long compared

More information

Physics 221 Experiment 5: Magnetic Fields

Physics 221 Experiment 5: Magnetic Fields Physics 221 Experiment 5: Magnetic Fields August 25, 2007 ntroduction This experiment will examine the properties of magnetic fields. Magnetic fields can be created in a variety of ways, and are also found

More information

J.J. Thomson, Cathode Rays and the Electron

J.J. Thomson, Cathode Rays and the Electron Introduction Voltage source Experimenters had noticed that sparks travel through rarefied (i.e. low pressure) air since the time of Franklin. The basic setup was to have two metal plates inside a glass

More information

FORCE ON A CURRENT IN A MAGNETIC FIELD

FORCE ON A CURRENT IN A MAGNETIC FIELD 7/16 Force current 1/8 FORCE ON A CURRENT IN A MAGNETIC FIELD PURPOSE: To study the force exerted on an electric current by a magnetic field. BACKGROUND: When an electric charge moves with a velocity v

More information

Lab 11: Magnetic Fields Name:

Lab 11: Magnetic Fields Name: Lab 11: Magnetic Fields Name: Group Members: Date: TA s Name: Objectives: To measure and understand the magnetic field of a bar magnet. To measure and understand the magnetic field of an electromagnet,

More information

1. Units of a magnetic field might be: A. C m/s B. C s/m C. C/kg D. kg/c s E. N/C m ans: D

1. Units of a magnetic field might be: A. C m/s B. C s/m C. C/kg D. kg/c s E. N/C m ans: D Chapter 28: MAGNETIC FIELDS 1 Units of a magnetic field might be: A C m/s B C s/m C C/kg D kg/c s E N/C m 2 In the formula F = q v B: A F must be perpendicular to v but not necessarily to B B F must be

More information

Experiment 7: Forces and Torques on Magnetic Dipoles

Experiment 7: Forces and Torques on Magnetic Dipoles MASSACHUSETTS INSTITUTE OF TECHNOLOY Department of Physics 8. Spring 5 OBJECTIVES Experiment 7: Forces and Torques on Magnetic Dipoles 1. To measure the magnetic fields due to a pair of current-carrying

More information

Cathode Ray Tube. Introduction. Functional principle

Cathode Ray Tube. Introduction. Functional principle Introduction The Cathode Ray Tube or Braun s Tube was invented by the German physicist Karl Ferdinand Braun in 897 and is today used in computer monitors, TV sets and oscilloscope tubes. The path of the

More information

The purposes of this experiment are to test Faraday's Law qualitatively and to test Lenz's Law.

The purposes of this experiment are to test Faraday's Law qualitatively and to test Lenz's Law. 260 17-1 I. THEORY EXPERIMENT 17 QUALITATIVE STUDY OF INDUCED EMF Along the extended central axis of a bar magnet, the magnetic field vector B r, on the side nearer the North pole, points away from this

More information

Experiment 3: Magnetic Fields of a Bar Magnet and Helmholtz Coil

Experiment 3: Magnetic Fields of a Bar Magnet and Helmholtz Coil MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics 8.02 Spring 2006 Experiment 3: Magnetic Fields of a Bar Magnet and Helmholtz Coil OBJECTIVES 1. To learn how to visualize magnetic field lines

More information

Review Questions PHYS 2426 Exam 2

Review Questions PHYS 2426 Exam 2 Review Questions PHYS 2426 Exam 2 1. If 4.7 x 10 16 electrons pass a particular point in a wire every second, what is the current in the wire? A) 4.7 ma B) 7.5 A C) 2.9 A D) 7.5 ma E) 0.29 A Ans: D 2.

More information

Physics Spring Experiment #8 1 Experiment #8, Magnetic Forces Using the Current Balance

Physics Spring Experiment #8 1 Experiment #8, Magnetic Forces Using the Current Balance Physics 182 - Spring 2012 - Experiment #8 1 Experiment #8, Magnetic Forces Using the Current Balance 1 Purpose 1. To demonstrate and measure the magnetic forces between current carrying wires. 2. To verify

More information

Physics 42 Lab 4 Fall 2012 Cathode Ray Tube (CRT)

Physics 42 Lab 4 Fall 2012 Cathode Ray Tube (CRT) Physics 42 Lab 4 Fall 202 Cathode Ray Tube (CRT) PRE-LAB Read the background information in the lab below and then derive this formula for the deflection. D = LPV defl 2 SV accel () Redraw the diagram

More information

Magnetic Fields and Their Effects

Magnetic Fields and Their Effects Name Date Time to Complete h m Partner Course/ Section / Grade Magnetic Fields and Their Effects This experiment is intended to give you some hands-on experience with the effects of, and in some cases

More information

Ampere's Law. Introduction. times the current enclosed in that loop: Ampere's Law states that the line integral of B and dl over a closed path is 0

Ampere's Law. Introduction. times the current enclosed in that loop: Ampere's Law states that the line integral of B and dl over a closed path is 0 1 Ampere's Law Purpose: To investigate Ampere's Law by measuring how magnetic field varies over a closed path; to examine how magnetic field depends upon current. Apparatus: Solenoid and path integral

More information

CHARGED PARTICLES & MAGNETIC FIELDS - WebAssign

CHARGED PARTICLES & MAGNETIC FIELDS - WebAssign Name: Period: Due Date: Lab Partners: CHARGED PARTICLES & MAGNETIC FIELDS - WebAssign Purpose: Use the CP program from Vernier to simulate the motion of charged particles in Magnetic and Electric Fields

More information

ELECTRIC FIELD LINES AND EQUIPOTENTIAL SURFACES

ELECTRIC FIELD LINES AND EQUIPOTENTIAL SURFACES ELECTRIC FIELD LINES AND EQUIPOTENTIAL SURFACES The purpose of this lab session is to experimentally investigate the relation between electric field lines of force and equipotential surfaces in two dimensions.

More information

Magnetism. d. gives the direction of the force on a charge moving in a magnetic field. b. results in negative charges moving. clockwise.

Magnetism. d. gives the direction of the force on a charge moving in a magnetic field. b. results in negative charges moving. clockwise. Magnetism 1. An electron which moves with a speed of 3.0 10 4 m/s parallel to a uniform magnetic field of 0.40 T experiences a force of what magnitude? (e = 1.6 10 19 C) a. 4.8 10 14 N c. 2.2 10 24 N b.

More information

Physics 2B. Lecture 29B

Physics 2B. Lecture 29B Physics 2B Lecture 29B "There is a magnet in your heart that will attract true friends. That magnet is unselfishness, thinking of others first. When you learn to live for others, they will live for you."

More information

LABORATORY V MAGNETIC FIELDS AND FORCES

LABORATORY V MAGNETIC FIELDS AND FORCES LABORATORY V MAGNETIC FIELDS AND FORCES Magnetism plays a large part in our modern world's technology. Magnets are used today to image parts of the body, to explore the mysteries of the human brain, and

More information

Chapter 22 Magnetism

Chapter 22 Magnetism 22.6 Electric Current, Magnetic Fields, and Ampere s Law Chapter 22 Magnetism 22.1 The Magnetic Field 22.2 The Magnetic Force on Moving Charges 22.3 The Motion of Charged particles in a Magnetic Field

More information

One- and Two-dimensional Motion

One- and Two-dimensional Motion PHYS-101 LAB-02 One- and Two-dimensional Motion 1. Objective The objectives of this experiment are: to measure the acceleration of gravity using one-dimensional motion to demonstrate the independence of

More information

Fall 12 PHY 122 Homework Solutions #8

Fall 12 PHY 122 Homework Solutions #8 Fall 12 PHY 122 Homework Solutions #8 Chapter 27 Problem 22 An electron moves with velocity v= (7.0i - 6.0j)10 4 m/s in a magnetic field B= (-0.80i + 0.60j)T. Determine the magnitude and direction of the

More information

Conceptual: 1, 3, 5, 6, 8, 16, 18, 19. Problems: 4, 6, 8, 11, 16, 20, 23, 27, 34, 41, 45, 56, 60, 65. Conceptual Questions

Conceptual: 1, 3, 5, 6, 8, 16, 18, 19. Problems: 4, 6, 8, 11, 16, 20, 23, 27, 34, 41, 45, 56, 60, 65. Conceptual Questions Conceptual: 1, 3, 5, 6, 8, 16, 18, 19 Problems: 4, 6, 8, 11, 16, 20, 23, 27, 34, 41, 45, 56, 60, 65 Conceptual Questions 1. The magnetic field cannot be described as the magnetic force per unit charge

More information

33. Magnetic Field: Permanent Magnet

33. Magnetic Field: Permanent Magnet Name Period Date 33. Magnetic Field: Permanent Magnet Driving Question How do you think the strength of the magnetic field of a permanent magnet changes as you get farther away from the magnet. Background

More information

Experiment 6: Magnetic Force on a Current Carrying Wire

Experiment 6: Magnetic Force on a Current Carrying Wire Chapter 8 Experiment 6: Magnetic Force on a Current Carrying Wire 8.1 Introduction Maricourt (1269) is credited with some of the original work in magnetism. He identified the magnetic force centers of

More information

Physics 126 Practice Exam #3 Professor Siegel

Physics 126 Practice Exam #3 Professor Siegel Physics 126 Practice Exam #3 Professor Siegel Name: Lab Day: 1. Which one of the following statements concerning the magnetic force on a charged particle in a magnetic field is true? A) The magnetic force

More information

Magnetic Field and Magnetic Forces

Magnetic Field and Magnetic Forces Chapter 27 Magnetic Field and Magnetic Forces PowerPoint Lectures for University Physics, Thirteenth Edition Hugh D. Young and Roger A. Freedman Lectures by Wayne Anderson Goals for Chapter 27 Magnets

More information

Acceleration of Gravity Lab Basic Version

Acceleration of Gravity Lab Basic Version Acceleration of Gravity Lab Basic Version In this lab you will explore the motion of falling objects. As an object begins to fall, it moves faster and faster (its velocity increases) due to the acceleration

More information

EXPERIMENT III EXPERIMENTS WITH AN ELECTRON BEAM

EXPERIMENT III EXPERIMENTS WITH AN ELECTRON BEAM EXPERIMENT III EXPERIMENTS WITH AN ELECTRON BEAM An electron beam is a collection of free electrons, all traveling in approximately the same direction with the approximately the same velocity. While it

More information

EXCEL EXERCISE AND ACCELERATION DUE TO GRAVITY

EXCEL EXERCISE AND ACCELERATION DUE TO GRAVITY EXCEL EXERCISE AND ACCELERATION DUE TO GRAVITY Objective: To learn how to use the Excel spreadsheet to record your data, calculate values and make graphs. To analyze the data from the Acceleration Due

More information

Three-dimensional figure showing the operation of the CRT. The dotted line shows the path traversed by an example electron.

Three-dimensional figure showing the operation of the CRT. The dotted line shows the path traversed by an example electron. Physics 241 Lab: Cathode Ray Tube http://bohr.physics.arizona.edu/~leone/ua/ua_spring_2010/phys241lab.html NAME: Section 1: 1.1. A cathode ray tube works by boiling electrons off a cathode heating element

More information

Chapter 19 Magnetic Forces and Fields

Chapter 19 Magnetic Forces and Fields Chapter 19 Magnetic Forces and Fields Student: 3. The magnetism of the Earth acts approximately as if it originates from a huge bar magnet within the Earth. Which of the following statements are true?

More information

Experiment 9: Biot -Savart Law with Helmholtz Coil

Experiment 9: Biot -Savart Law with Helmholtz Coil Experiment 9: Biot -Savart Law with Helmholtz Coil ntroduction n this lab we will study the magnetic fields of circular current loops using the Biot-Savart law. The Biot-Savart Law states the magnetic

More information

Multiple Choice Questions for Physics 1 BA113 Chapter 23 Electric Fields

Multiple Choice Questions for Physics 1 BA113 Chapter 23 Electric Fields Multiple Choice Questions for Physics 1 BA113 Chapter 23 Electric Fields 63 When a positive charge q is placed in the field created by two other charges Q 1 and Q 2, each a distance r away from q, the

More information

MAGNETIC FORCE ON AN ELECTRIC CHARGE

MAGNETIC FORCE ON AN ELECTRIC CHARGE DO PHYSICS ONLINE MOTORS AND GENERATORS MAGNETIC ORCE ON AN ELECTRIC CHARGE Experiments show that moing electric charges are deflected in magnetic fields. Hence, moing electric charges experience forces

More information

Experiment 3: Magnetic Fields of a Bar Magnet and Helmholtz Coil

Experiment 3: Magnetic Fields of a Bar Magnet and Helmholtz Coil MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics 8.02 Spring 2009 Experiment 3: Magnetic Fields of a Bar Magnet and Helmholtz Coil OBJECTIVES 1. To learn how to visualize magnetic field lines

More information

THE SPRING CONSTANT. Apparatus: A spiral spring, a set of weights, a weight hanger, a balance, a stop watch, and a twometer

THE SPRING CONSTANT. Apparatus: A spiral spring, a set of weights, a weight hanger, a balance, a stop watch, and a twometer THE SPRING CONSTANT Objective: To determine the spring constant of a spiral spring by Hooe s law and by its period of oscillatory motion in response to a weight. Apparatus: A spiral spring, a set of weights,

More information

Chapter 27 Magnetic Field and Magnetic Forces

Chapter 27 Magnetic Field and Magnetic Forces Chapter 27 Magnetic Field and Magnetic Forces - Magnetism - Magnetic Field - Magnetic Field Lines and Magnetic Flux - Motion of Charged Particles in a Magnetic Field - Applications of Motion of Charged

More information

Chapter 4. Kinematics - Velocity and Acceleration. 4.1 Purpose. 4.2 Introduction

Chapter 4. Kinematics - Velocity and Acceleration. 4.1 Purpose. 4.2 Introduction Chapter 4 Kinematics - Velocity and Acceleration 4.1 Purpose In this lab, the relationship between position, velocity and acceleration will be explored. In this experiment, friction will be neglected.

More information

THE CONSERVATION OF ENERGY - PENDULUM -

THE CONSERVATION OF ENERGY - PENDULUM - THE CONSERVATION OF ENERGY - PENDULUM - Introduction The purpose of this experiment is to measure the potential energy and the kinetic energy of a mechanical system and to quantitatively compare the two

More information

Experiment #8: Magnetic Forces

Experiment #8: Magnetic Forces Experiment #8: Magnetic Forces Purpose: To study the nature of magnetic forces exerted on currents. Equipment: Magnet Assembly and Stand Set of Current Loop PC oards Triple-Arm Pan alance 0 15 V dc Variable

More information

ACTIVITY SIX CONSERVATION OF MOMENTUM ELASTIC COLLISIONS

ACTIVITY SIX CONSERVATION OF MOMENTUM ELASTIC COLLISIONS 1 PURPOSE ACTIVITY SIX CONSERVATION OF MOMENTUM ELASTIC COLLISIONS For this experiment, the Motion Visualizer (MV) is used to capture the motion of two frictionless carts moving along a flat, horizontal

More information

Physics 30 Worksheet #10 : Magnetism From Electricity

Physics 30 Worksheet #10 : Magnetism From Electricity Physics 30 Worksheet #10 : Magnetism From Electricity 1. Draw the magnetic field surrounding the wire showing electron current below. x 2. Draw the magnetic field surrounding the wire showing electron

More information

Physics 9 Fall 2009 Homework 7 - Solutions

Physics 9 Fall 2009 Homework 7 - Solutions Physics 9 Fall 009 Homework 7 - s 1. Chapter 33 - Exercise 10. At what distance on the axis of a current loop is the magnetic field half the strength of the field at the center of the loop? Give your answer

More information

Phys222 Winter 2012 Quiz 4 Chapters 29-31. Name

Phys222 Winter 2012 Quiz 4 Chapters 29-31. Name Name If you think that no correct answer is provided, give your answer, state your reasoning briefly; append additional sheet of paper if necessary. 1. A particle (q = 5.0 nc, m = 3.0 µg) moves in a region

More information

Magnetism. ***WARNING: Keep magnets away from computers and any computer disks!***

Magnetism. ***WARNING: Keep magnets away from computers and any computer disks!*** Magnetism This lab is a series of experiments investigating the properties of the magnetic field. First we will investigate the polarity of magnets and the shape of their field. Then we will explore the

More information

FREE FALL. Introduction. Reference Young and Freedman, University Physics, 12 th Edition: Chapter 2, section 2.5

FREE FALL. Introduction. Reference Young and Freedman, University Physics, 12 th Edition: Chapter 2, section 2.5 Physics 161 FREE FALL Introduction This experiment is designed to study the motion of an object that is accelerated by the force of gravity. It also serves as an introduction to the data analysis capabilities

More information

Bohr s Model and Emission Spectra of Hydrogen and Helium

Bohr s Model and Emission Spectra of Hydrogen and Helium PHYS-01 LAB-03 Bohr s Model and Emission Spectra of Hydrogen and Helium 1. Objective The objective of this experiment is to study the emission spectrum of hydrogen and to understand its origin in terms

More information

The Magnetic Field of a Permanent Magnet

The Magnetic Field of a Permanent Magnet Introduction The of a Permanent Magnet A bar magnet is called a dipole since it has two poles, commonly labeled North and South. Breaking a magnet in two does not produce two isolated poles; each fragment

More information

EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME 1 - D.C. CIRCUITS

EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME 1 - D.C. CIRCUITS EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME - D.C. CIRCUITS Be able to use circuit theory to determine voltage, current and resistance in direct

More information

Circuits and Resistivity

Circuits and Resistivity Circuits and Resistivity Look for knowledge not in books but in things themselves. W. Gilbert OBJECTIVES To learn the use of several types of electrical measuring instruments in DC circuits. To observe

More information

Physics 1653 Exam 3 - Review Questions

Physics 1653 Exam 3 - Review Questions Physics 1653 Exam 3 - Review Questions 3.0 Two uncharged conducting spheres, A and B, are suspended from insulating threads so that they touch each other. While a negatively charged rod is held near, but

More information

Experimental Question 1: Levitation of Conductors in an Oscillating Magnetic Field SOLUTION ( )

Experimental Question 1: Levitation of Conductors in an Oscillating Magnetic Field SOLUTION ( ) a. Using Faraday s law: Experimental Question 1: Levitation of Conductors in an Oscillating Magnetic Field SOLUTION The overall sign will not be graded. For the current, we use the extensive hints in the

More information

Chapter 14 Magnets and

Chapter 14 Magnets and Chapter 14 Magnets and Electromagnetism How do magnets work? What is the Earth s magnetic field? Is the magnetic force similar to the electrostatic force? Magnets and the Magnetic Force! We are generally

More information

ACCELERATION DUE TO GRAVITY

ACCELERATION DUE TO GRAVITY EXPERIMENT 1 PHYSICS 107 ACCELERATION DUE TO GRAVITY Skills you will learn or practice: Calculate velocity and acceleration from experimental measurements of x vs t (spark positions) Find average velocities

More information

Newton s Third Law, Momentum, Center of Mass

Newton s Third Law, Momentum, Center of Mass Team: Newton s Third Law, Momentum, Center of Mass Newton s Third Law is a deep statement on the symmetry of interaction between any two bodies in the universe. How is the pull of the earth on the moon

More information

Newton s Third Law, Momentum, Center of Mass

Newton s Third Law, Momentum, Center of Mass Team: Newton s Third Law, Momentum, Center of Mass Part I. Newton s Third Law Atomic Springs When you push against a wall, you feel a force in the opposite direction. The harder you push, the harder the

More information

Determining the Critical Potentials for Helium: The Franck-Hertz Experiment

Determining the Critical Potentials for Helium: The Franck-Hertz Experiment Determining the Critical Potentials for Helium: The Franck-Hertz Experiment Trent H. Stein, Michele L. Stover, and David A. Dixon Department of Chemistry, The University of Alabama, Shelby Hall, Tuscaloosa,

More information

Appendix E: Graphing Data

Appendix E: Graphing Data You will often make scatter diagrams and line graphs to illustrate the data that you collect. Scatter diagrams are often used to show the relationship between two variables. For example, in an absorbance

More information

Module 3 : Electromagnetism Lecture 13 : Magnetic Field

Module 3 : Electromagnetism Lecture 13 : Magnetic Field Module 3 : Electromagnetism Lecture 13 : Magnetic Field Objectives In this lecture you will learn the following Electric current is the source of magnetic field. When a charged particle is placed in an

More information

Magnetic Fields Lab. Station #1 à Determining Magnetic Flux Lines

Magnetic Fields Lab. Station #1 à Determining Magnetic Flux Lines Magnetic Fields Lab Regents Physics Name Mr. Putnam Station #1 à Determining Magnetic Flux Lines You must FIRST FIND WHICH END of your compass needle that points Geographic North. THIS WILL BE THE NORTH

More information

ELECTRICITYt. Electromagnetism

ELECTRICITYt. Electromagnetism ELECTRICITYt Electromagnetism Subject area : Physics Topic focus : magnetic properties, magnetic field, the Earth s magnetic field, magnetic field of an electric wire. Learning Aims : Polarity of bar magnets

More information

Candidate Number. General Certificate of Education Advanced Level Examination June 2012

Candidate Number. General Certificate of Education Advanced Level Examination June 2012 entre Number andidate Number Surname Other Names andidate Signature General ertificate of Education dvanced Level Examination June 212 Physics PHY4/1 Unit 4 Fields and Further Mechanics Section Monday

More information

Magnetism, a history. Existence of a Magnetic Field, B. Magnetic Force on a charged particle. The particle in the figure

Magnetism, a history. Existence of a Magnetic Field, B. Magnetic Force on a charged particle. The particle in the figure Existence of a Magnetic Field, B Magnetic field, B, is a vector You may be familiar with bar magnets have a magnetic field similar to electric field of dipoles Amazing experimental finding: there is a

More information

AS CHALLENGE PAPER 2014

AS CHALLENGE PAPER 2014 AS CHALLENGE PAPER 2014 Name School Total Mark/50 Friday 14 th March Time Allowed: One hour Attempt as many questions as you can. Write your answers on this question paper. Marks allocated for each question

More information

Graphical Presentation of Data

Graphical Presentation of Data Graphical Presentation of Data Guidelines for Making Graphs Titles should tell the reader exactly what is graphed Remove stray lines, legends, points, and any other unintended additions by the computer

More information

Experiment 5: Magnetic Fields of a Bar Magnet and of the Earth

Experiment 5: Magnetic Fields of a Bar Magnet and of the Earth MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics 8.02 Spring 2005 Experiment 5: Magnetic Fields of a Bar Magnet and of the Earth OBJECTIVES 1. To examine the magnetic field associated with a

More information

Lab 7: Rotational Motion

Lab 7: Rotational Motion Lab 7: Rotational Motion Equipment: DataStudio, rotary motion sensor mounted on 80 cm rod and heavy duty bench clamp (PASCO ME-9472), string with loop at one end and small white bead at the other end (125

More information

1. The diagram below represents magnetic lines of force within a region of space.

1. The diagram below represents magnetic lines of force within a region of space. 1. The diagram below represents magnetic lines of force within a region of space. 4. In which diagram below is the magnetic flux density at point P greatest? (1) (3) (2) (4) The magnetic field is strongest

More information

Objectives 200 CHAPTER 4 RESISTANCE

Objectives 200 CHAPTER 4 RESISTANCE Objectives Explain the differences among conductors, insulators, and semiconductors. Define electrical resistance. Solve problems using resistance, voltage, and current. Describe a material that obeys

More information

My lecture slides are posted at Information for Physics 112 midterm, Wednesday, May 2

My lecture slides are posted at  Information for Physics 112 midterm, Wednesday, May 2 My lecture slides are posted at http://www.physics.ohio-state.edu/~humanic/ Information for Physics 112 midterm, Wednesday, May 2 1) Format: 10 multiple choice questions (each worth 5 points) and two show-work

More information

The Structure of the Atom

The Structure of the Atom The Structure of the Atom Section 4.1 Early Ideas About Matter Section 4.2 Defining the Atom Section 4.3 How Atoms Differ Section 4.4 Unstable Nuclei and Radioactive Decay Click a hyperlink or folder tab

More information

5. Measurement of a magnetic field

5. Measurement of a magnetic field H 5. Measurement of a magnetic field 5.1 Introduction Magnetic fields play an important role in physics and engineering. In this experiment, three different methods are examined for the measurement of

More information

A Determination of g, the Acceleration Due to Gravity, from Newton's Laws of Motion

A Determination of g, the Acceleration Due to Gravity, from Newton's Laws of Motion A Determination of g, the Acceleration Due to Gravity, from Newton's Laws of Motion Objective In the experiment you will determine the cart acceleration, a, and the friction force, f, experimentally for

More information

Scientific Graphing in Excel 2010

Scientific Graphing in Excel 2010 Scientific Graphing in Excel 2010 When you start Excel, you will see the screen below. Various parts of the display are labelled in red, with arrows, to define the terms used in the remainder of this overview.

More information

Lab 7: Magnetic Field of a Permanent Magnet (Magnetic Field Sensor)

Lab 7: Magnetic Field of a Permanent Magnet (Magnetic Field Sensor) of a Permanent Magnet (Magnetic Field Sensor) Equipment Needed Qty Equipment Needed Qty Magnetic Field Sensor (CI-6520A) 1 Meter stick, non-metal 1 Magnet*, disk, Neodymium, 1/2 or 3/4 (EM-8648) 1 Small

More information

Physics 1050 Experiment 2. Acceleration Due to Gravity

Physics 1050 Experiment 2. Acceleration Due to Gravity Acceleration Due to Gravity Prelab Questions These questions need to be completed before entering the lab. Please show all workings. Prelab 1: For a falling ball, which bounces, draw the expected shape

More information

Magnetic Force on a Current-Carrying Wire

Magnetic Force on a Current-Carrying Wire Title: Original Version: Revision: Authors: Appropriate Level: Abstract: Time Required: NY Standards Met: AP Physics Learning Objective: Magnetic Force on a Current-Carrying Wire 11 November 2006 24 June

More information

Mapping the Magnetic Field

Mapping the Magnetic Field I Mapping the Magnetic Field Mapping the Magnetic Field Vector Fields The electric field, E, and the magnetic field, B, are two examples of what are termed vector fields, quantities which have both magnitude

More information

Experiment 8: Undriven & Driven RLC Circuits

Experiment 8: Undriven & Driven RLC Circuits Experiment 8: Undriven & Driven RLC Circuits Answer these questions on a separate sheet of paper and turn them in before the lab 1. RLC Circuits Consider the circuit at left, consisting of an AC function

More information

CET Moving Charges & Magnetism

CET Moving Charges & Magnetism CET 2014 Moving Charges & Magnetism 1. When a charged particle moves perpendicular to the direction of uniform magnetic field its a) energy changes. b) momentum changes. c) both energy and momentum

More information

) 0.7 =1.58 10 2 N m.

) 0.7 =1.58 10 2 N m. Exam 2 Solutions Prof. Paul Avery Prof. Andrey Korytov Oct. 29, 2014 1. A loop of wire carrying a current of 2.0 A is in the shape of a right triangle with two equal sides, each with length L = 15 cm as

More information

FRICTION, WORK, AND THE INCLINED PLANE

FRICTION, WORK, AND THE INCLINED PLANE FRICTION, WORK, AND THE INCLINED PLANE Objective: To measure the coefficient of static and inetic friction between a bloc and an inclined plane and to examine the relationship between the plane s angle

More information

Physics 121 Sample Common Exam 3 NOTE: ANSWERS ARE ON PAGE 6. Instructions: 1. In the formula F = qvxb:

Physics 121 Sample Common Exam 3 NOTE: ANSWERS ARE ON PAGE 6. Instructions: 1. In the formula F = qvxb: Physics 121 Sample Common Exam 3 NOTE: ANSWERS ARE ON PAGE 6 Signature Name (Print): 4 Digit ID: Section: Instructions: Answer all questions 24 multiple choice questions. You may need to do some calculation.

More information